Trisomy 9 mosaicism and XX sex reversalHow to cite this article: Solomon BD, Turner CE, Klugman D, Sparks SE. 2007. Trisomy 9 mosaicism and XX sex reversal. Am J Med Genet Part A 143A:2688–2691.

We report on a case of a phenotypic male infant who was referred to the genetics service due to dysmorphic features and congenital cardiac anomalies. Dysmorphic features included low‐set, posteriorly rotated ears with squared, simple helices, midface hypoplasia, a broad nasal root with wide nasal alae, small mouth, micrognathia, short neck, overlapping fingers, rocker‐bottom feet, prominent heels, and hypoplastic toenails. The phallus was normal and no testes were palpable in the scrotal sac. Cardiac anomalies included tricuspid atresia and a ventricular septal defect. The karyotype was 46,XX. Diagnostic microarray demonstrated evidence for trisomy 9 mosaicism, metaphase FISH revealed trisomy 9 on 7% of cultured cells, and interphase FISH analysis of a peripheral blood smear showed trisomy 9 in 78% of the cells examined. This is the first reported case of XX sex reversal in a patient with trisomy 9 mosaicism. © 2007 Wiley‐Liss, Inc.